CN101427002A - Method of controlling operation of rock drilling rig, and rock drilling rig - Google Patents

Abstract

A method of controlling a rock drilling rig (1) and a rock drilling rig (1). The flow rate (FLOW) of the flushing medium of the rock drilling rig (1) is determined and the operation of the rock drilling rig (1) is controlled based on the flow rate (FLOW) determined by influencing the pressure (p_FLOW) of the flushing medium.

Description

Method of controlling operation of rock drilling rig and rock drilling rig

technical field

The invention relates to a method of controlling the operation of a rock drilling rig, wherein a flow rate of a flushing medium of the rock drilling rig is determined and the operation of the rock drilling rig is controlled based on the flow rate of the flushing medium.

The invention further relates to a rock drilling rig comprising means for feeding a flushing medium into the borehole to remove cuttings produced during drilling out of the borehole for determining Measuring means for the flow rate of the flushing medium to be fed into the borehole, and at least one control unit for controlling the operation of the rock drilling rig based on the flow rate of the flushing medium to be fed into the borehole.

Background technique

Rock drilling rigs and rock drilling machines arranged therein are used, for example, for rock drilling and excavation in underground mines, quarries and surface construction sites. Typically, drilling involves the use of four different functions or parts simultaneously, namely, rotating the drill rod within the borehole being drilled, by the impact of the percussion device on the drill bit via the shank extending from the percussion device and the drill rod. Percussion on the rock, and forward feeding of the rock drilling machine in the borehole being drilled, and flushing to remove drilling waste, ie cuttings, from the borehole being drilled. In so-called rotary applications, again only three sections are used, since these applications do not involve impacting the rock by impact on the shank by the impact device. Furthermore, a so-called DTH (Down Hole) application is used, where an impact piston located in the drill pipe at the bottom of the hole and not on the shank directly impacts on the drill bit. Thus, the breaking of the rock takes place mainly due to the impact of the impact, while the purpose of the rotation is mainly to ensure that the inserts of the drill bit or other working parts of the drill bit at the outermost end of the drill rod always apply the impact at new points in the rock. This feed is such that sufficient contact is maintained between the drill bit and the rock.

Successful flushing, ie the successful removal of cuttings from within the borehole being drilled, is very important for efficient drilling involved. During drilling, successful drilling is quickly jeopardized if problems occur in flushing. US 6 637 522 discloses a solution for controlling the work of rock drilling equipment during drilling. In the solution disclosed in US 6 637 522 the flushing flow is measured and the feed and/or rotation speed is controlled based on the measured flushing flow. According to disclosed embodiments, when flushing flow is reduced, feed and/or rotation is stopped to avoid drilling overload conditions. WO 2005/064111 discloses a solution in which the aim is to control the flushing power based at least in part on the depth of the hole being drilled so that no more power than necessary is used for flushing than is necessary for the depth of the hole being drilled. The aim of this solution is therefore to control the total power, which includes at least the percussion and/or rotational and flushing power consumed by chiseling.

Contents of the invention

The object of the present invention is to provide a novel solution for controlling the operation of rock drilling rigs based on the flow rate of the flushing medium.

The method according to the invention is characterized in that the operation of the rock drilling rig is controlled on the basis of the flow rate determined by influencing the pressure of the flushing medium.

The rock drilling rig according to the invention is characterized in that the control unit is configured to control the operation of the rock drilling rig on the basis of the flow rate determined by influencing the pressure of the flushing medium.

A flow rate of a flushing medium of a rock drilling rig is determined and operation of the rock drilling rig is controlled based on the flow rate of the flushing medium. The operation of the rock drilling rig is controlled based on the flow rate of the flushing medium by influencing the pressure of said flushing medium. According to an embodiment, the operation of the rock drilling rig is controlled by increasing the pressure of the flushing medium.

By controlling the operation of the rock drilling rig by influencing the pressure of the flushing medium, the aim is to clear blockages formed in the flushing channel system of the rock drilling rig without affecting other parts of the drilling. When a blockage is about to form in the flushing channel system, the flow rate of the flushing medium in the flushing channel system is reduced, but the purpose is to clear the blockage by increasing the pressure of the flushing medium and maintain the flow rate of the flushing medium at least at the setting for which it is set setting group while maintaining normal drilling work. At the same time, the flushing function is ensured and the strain on the drilling device is reduced.

Description of drawings

Some embodiments of the invention are described in more detail in the accompanying drawings, in which:

Figure 1 is a schematic side view showing a rock drilling rig;

2 and 3 are schematic views showing systems for measuring the flow rate of the flushing medium and for measuring the control pressure.

For the sake of clarity, the drawings show embodiments of the invention in a simplified manner. In the drawings, the same reference numerals denote the same elements.

Detailed ways

FIG. 1 schematically shows the structure of a rock drilling rig 1 . The rock drilling rig 1 comprises a movable carrier 2 provided with an arm 3 , the free end of which is provided with a feed beam 4 . Furthermore, the feed beam 4 is provided with a rock drilling machine 5 which is movable relative to the feed beam 4 . The rock drilling rig 1 including devices connected thereto is driven by power generated by an engine 6 provided on the carrier 2 so that the rock drilling rig 1 is an independently moving and working unit. Typically, the engine 6 is an internal combustion engine, such as a diesel engine. The rock drilling rig 1 according to FIG. 1 further comprises a compressor 7 driven by the engine 6, so that the compressed air generated by the compressor 7 is used to flush the borehole 8 to remove drilling waste, i.e. cuttings, from the borehole 8. remove. In this case, compressed air used as a flushing medium is fed from the compressor 7 through the tool 10 of the rock drilling machine to the borehole 8 through a system of flushing channels whereby the compressed air removes cuttings from the rock out of the drill hole. Hole 8. The flushing channel system comprises a flushing line 9 leading from the compressor 7 to the rock drilling machine 5 and in the rock drilling machine 5 the flushing channel passes through the shank, the drill rod and the drill bit, which for clarity the shank, the drill rod and The drill bit is not shown in Figure 1, but its basic structure and principles will be apparent to those skilled in the art. From the mouth of the borehole the cuttings are sucked out to the dust separator 11 through a hose included in the collection system. The basic structure and operation of the rock drilling rig 1 and the rock drilling machine 5 are known per se to a person skilled in the art, so they will not be described in further detail here.

When the rock to be drilled is solid rock, the need for flushing is very small. Whereas in soft rock, especially when drilling large-sized holes, flushing is extremely necessary and the amount of cuttings removed from the rock is high, which means that there is a risk of the flushing channel system being blocked. In addition to rock properties and hole size, the need for flushing is influenced by, for example, the type of drill pipe and bit and the depth of the borehole.

Figures 2 and 3 schematically show an embodiment of implementing the solution. FIG. 2 shows a measuring device 12 arranged in connection with the flushing line 9 of the rock drilling rig 1 for measuring the flow rate FLOW of the flushing medium flowing in the flushing channel system, ie shown in FIG. 1 For measuring the volumetric flow rate of compressed air. As an alternative to the flushing line 9 , the measuring device can also be placed differently in the flushing channel system. The measuring device 12 for the flow rate of the flushing medium may comprise, for example, a Venturi tube-based measuring device for measuring the remaining pressure difference over the Venturi tube in a manner known per se. However, the measuring device 12 can be embodied in a number of different ways, so that in one way or in another it is possible to measure the flow rate FLOW of the flushing medium flowing in the flushing channel system or a quantity proportional thereto. As an alternative to using a Venturi tube, the difference between the pressures measured at any two different points within the irrigation channel system can be used to measure the flow rate of the irrigation medium. Thus, the flow rate of the flushing medium can eg be determined based on the difference between the pressures acting on opposite sides of the directional control valve, or on the basis of the difference between the pressures acting at the extreme ends of the flushing channel system. Typically, the unit for the flow rate of the flushing medium is m ³ /min. The information FLOW describing the flow rate of the flushing medium is transmitted to the control unit 13, which may be a control unit controlling only flushing, or a control unit controlling the operation of the entire rock drilling rig 1 . Furthermore, the flow rate of the flushing medium can be presented to the user graphically or numerically on the user interface of the rock drilling rig 1 .

The flow rate FLOW of the flushing medium measured from the flushing channel system is compared with a first limit value FLOW _LIMIT1 set for the flow rate of the flushing medium. When the flow rate FLOW of the flushing medium through the flushing channel system falls below said first limit value FLOW _LIMIT1 of the flow rate of the flushing medium, this is interpreted as a blockage in the flushing channel system. In such a case, in the situation shown in FIG. 2 , the control unit 13 sends a control message CTRL to the pressure control valve 15 included in the flushing channel system and located in the compressor 7 and the directional control valve 14 to increase the control value of the valve, thereby increasing the pressure p_FLOW of the flushing medium flowing in the flushing channel system, and thus sending the flushing medium at a higher pressure to clear any blockage that may form in the flushing channel system . The pressure control valve 15 is used to set a desired pressure of the compressor 7 . The pressure control valve 15 may be, for example, a steplessly adjustable electric control valve, or may consist of several pressure control valves that have been preset to different pressure values. Of course, a blockage in the flushing channel system itself increases the pressure on the flushing medium, but according to this solution, the pressure of the flushing medium increases to a level significantly higher than that corresponding to such a pressure increase. The pressure p_FLOW of the flushing medium may be increased, for example so that the flow rate FLOW of the flushing medium is increased to a level corresponding to the original set value FLO _WSET of the flow rate of the flushing medium or to a level corresponding to the maximum allowable value p_FLOW _MAX of the pressure of the flushing medium, as in Figure 3 shows. The user interface of the rock drilling rig 1 can, for example, continuously display the actual instantaneous flow rate of the flushing medium as well as the aforementioned limit values graphically or numerically, so that the user can monitor how the drilling is going. In addition, the user interface may be provided with control elements or the like to enable the user to influence the aforementioned limit values at any time.

According to this solution, the aim is therefore to maintain the flushing flow at least at the set value in order to guarantee the flushing to work. When a blockage is about to form in the flushing channel system, i.e. in practice more typically in the flushing channel of the drill bit, the flow rate of the flushing medium in the flushing channel system drops, in this case maintained by increasing the pressure of the flushing medium Flush the opening of the channel system. The aim is therefore to return the flow rate FLOW of the flushing medium at least to the setpoint FLOW _SET set therefor, thus preventing the flushing channel system from being blocked, while maintaining normal drilling work. The approach according to this solution thus achieves in a simple manner the prevention of the flushing device being blocked during drilling.

Instead of the pressure control valve 15 , the pressure of the flushing medium can also be increased by changing the rotational speed of the rotor of the compressor 7 . In this case, for example, the control unit 13 sends control information to the compressor 7 for increasing the rotational speed of the rotor, which causes an increase in the volume flow of air and thus also in the pressure.

In addition, the pressure of the flushing medium can be controlled by adjusting the intake air of the compressor. The output pressure of the compressor can be influenced by limiting or opening the suction valve, for example by connecting a position servo to the spindle which moves the suction valve plate.

Instead of increasing the pressure of the flushing medium only after the flow rate FLOW of the flushing medium has dropped below the first limit value FLOW _LIMIT1 , the pressure can be increased immediately when the flow rate of the flushing medium starts to drop. In each case, the pressure of the flushing medium can be increased stepwise or in proportion to the decrease in the flow rate of the flushing medium.

If increasing the flushing pressure p_FLOW of the flushing medium does not succeed in returning the flow rate FLOW of the flushing medium to the normal speed but the flow rate of the flushing medium remains reduced, a second limit value FLOW _LIMIT2 of the flow rate FLOW of the flushing medium can be introduced into the device such that When the flow rate FLOW of the flushing medium decreases below this second limit value FLOW _LIMIT2 , the feeding work of the rock drilling equipment 1 is stopped by the control of the control unit 13, in this case, the drilling is no longer advanced and no drilling is generated. crumbs. When necessary, the drilling device can also be pulled back in the borehole 8 by control of the control unit 13 in order to return the flow of flushing medium.

As an alternative or in addition to the flow rate FLOW of the flushing medium, it is also possible to monitor the rate of change dFLOW in the flow rate FLOW of the flushing medium, such that any currently occurring flushing blockage, typically a drill bit blockage in practice, occurs after the measured flow rate FLOW drops to Before the first limit value FLOW _LIMIT1 , abrupt changes based on the flow rate FLOW of the flushing medium can already be observed very rapidly. The rate of change dFLOW of the flow rate FLOW of the flushing medium can eg be determined at the control unit 13 eg based on the difference of two or more successive measurements of the flow rate FLOW of the flushing medium. This value of the rate of change dFLOW is compared with a first limit value dFLOW _LIMIT1 set for the rate of change of the flow rate of the flushing medium. When the rate of change dFLOW of the flow rate FLOW exceeds the first limit value dFLOW _LIMIT1 , this is interpreted as a blockage in flushing, in which case the control unit 3 controls the pressure valve 15 in the flushing channel system to increase the pressure p_FLOW.

Similar to the way used with respect to the flow rate of the flushing medium, a second limit value dFLOW _LIMIT2 can also be determined for the rate of change of the flow rate of the flushing medium such that rock drilling is stopped by control of the control unit 13 when the rate of change exceeds said limit value The feeding function of the device, in which case the chisel is no longer advancing and no cuttings are produced. Also in this case, the drilling arrangement, also controlled by the control unit 13 , can be pulled back in the borehole 8 when required, in order to return the flow of flushing medium.

The control unit 13 may also further comprise means such as a comparison element for comparing the flow rate FLOW of the flushing medium with a corresponding set value FLOW _SET . In this case, after the blockage has been cleared and after the flow rate FLOW of the flushing medium has returned to the corresponding set value FLOW _SET , the control unit 13 can be controlled so that the pressure p_FLOW of the flushing medium returns to the value that was active during normal drilling conditions. Set point p_FLOW _SET for the pressure of the flushing medium.

To improve the flow return of the flushing medium, it is also possible to use a device in which a percussion device is used on the drilling unit when the drilling feed is stopped or while the drilling unit is being pulled back in the borehole. Shocks are applied to generate vibrations within the drilling rig. The purpose of such vibration is to enhance the loosening of drill cuttings adhering to the flushing channel system from the flushing channel system. The impact device is thus used to apply impacts on the shank of the rock drill. In order to prevent an excessively long distance between the shank and the percussion device during pulling back the drilling device, which prevents the effective impact of the percussion device on the shank, a pulling element such as a pulling piston can be arranged to be connected to the shank . The pulling element keeps the distance between the percussion device and the shank constant and optimal so that the percussion device can effectively impact on the shank and generate significant vibrations within the drilling device to facilitate the removal of drill cuttings.

Thus, the rock drilling rig 1 may comprise one or more control units 13, such that a control unit 13 may control the operation of the whole rock drilling rig, or each part of the drilling may be provided with its own control unit. The control unit may be, for example, a device comprising a microprocessor and/or a signal processor, and the device may comprise a memory capacity externally connected to the device to perform the necessary calculations and comparisons by software contained within the memory capacity process. The control unit may also be a device comprising only electronic circuits and having the necessary elements for producing a difference between two or more quantities, for example for determining the rate of change of the flow rate of said flushing medium, and for setting The determined flow rate or the rate of change of the flow rate is compared with corresponding limit values, which can be set by the user of the rock drilling rig 1 . The general structure and operating principles of such control units and devices are known per se to those skilled in the art.

Knowledge of the flow rate FLOW of the flushing flow can also be applied to automatically calibrate the flushing monitor. The main objective in the calibration is to determine the losses caused by the drilling rig, i.e. the losses caused by the shank, drill pipe and drill bit, that is, to determine when the drilling rig is not drilling, ie when the flushing channel system is fully open, through The flow rate of the flushing medium for the drilling rig. In calibration, the measurement provided by the measuring device 12 measuring the flow rate of the flushing medium is determined as true zero flow, ie when no flushing flow is provided at all, and as true full flushing flow. In addition to these two measuring points, however, other measuring points can also be used in the calibration. Calibration measurements thus obtained can be transferred directly to the unit carrying out the flushing monitoring to take into account small operating variations, for example due to production tolerances within the device included in the measuring device measuring the flow rate of the flushing flow. Such automatic calibration can be utilized both in factory calibrations and in calibrations performed at the drilling site. In factory calibration, variations due to different drilling rigs can be taken into account in the measurement of the flow rate of the flushing medium. Calibration at the drilling site can in turn be performed whenever desired, to compensate for drifts in the measuring device that occur over time, or to take into account changes in the measured values due to drilling conditions or the flow rate of the flushing medium during the drilling process. It may be effected that changes in the measured value of the flow rate are caused by changes in the drilling device, for example by replacement of a drill bit.

In the figures there is shown a solution for a rock drilling rig in which compressed air generated by a compressor 7 or another device suitable for generating compressed air is used as flushing medium. However, this solution can also be utilized in rock drilling rigs in which a pressurized fluid, which can for example be water, a mixture of water and air or a mixture of water and chemicals, is used as flushing medium. When the pressurized fluid is used as the flushing medium, the compressor is replaced by a pump, etc., which directly or indirectly sends the flushing medium to the rock drilling machine 5 through the flushing channel system through the power generated by the engine 6, and through the rock drill The tool 10 of the drilling rig 5 is fed into the borehole 8 , whereby the flushing medium pushes the cuttings removed from the rock out of the borehole 8 . In this case, the rock drilling rig must then of course also be provided with special reservoirs or connections for delivering flushing fluid to the rock drilling rig. The pressure of the flushing medium can then be increased in a manner substantially similar to that shown in connection with the examples above, however taking into account the differences in the operation of compressors and pumps apparent to those skilled in the art, as well as within the device due to fluid replacement Changes caused by air as a flushing medium.

In some cases, features disclosed in this application may be so used independently of other features. On the other hand, the features disclosed in this application can be combined to produce different combinations when necessary.

The drawings and the associated description are only intended to illustrate the idea of the invention. The invention may vary in its details within the scope of the claims.

Claims (21)

1. A method of controlling the operation of a rock drilling rig (1), wherein a flow rate (FLOW) of a flushing medium of the rock drilling rig (1) is determined and the rock drilling rig is controlled based on said flow rate (FLOW) of the flushing medium The work of (1) is characterized in that, determining the flow rate (FLOW) of the flushing medium of the rock drilling rig (1) based on the flow rate (FLOW) of the flushing medium flowing in the flushing channel system of the rock drilling rig (1), compares the flow rate of the flushing medium (FLOW) with the limit value set for the flow rate of the flushing medium (FLOW _LIMIT1 ), and When the flow rate (FLOW) of the flushing medium drops below the limit value (FLOW _LIMIT1 ), the pressure of the flushing medium (p_FLOW) is increased. 2. The method of claim 1, wherein, Determine the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium, comparing the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium with the corresponding first limit value (dFLOW _LIMIT1 ), and When the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium exceeds said first limit value (dFLOW _LIMIT1 ), the pressure of the flushing medium (p_FLOW) is increased. 3. The method according to claim 1 or 2, characterized in that the flow rate (FLOW) of the flushing medium is increased to a set value (FLOW _SET ) corresponding to the flow rate of the flushing medium by increasing the pressure (p_FLOW) of the flushing medium value. 4. Method according to any one of the preceding claims, characterized in that the pressure of the flushing medium (p_FLOW) is increased to the maximum permissible value (p_FLOW _MAX ) set therefor. 5. Method according to any one of the preceding claims, characterized in that the pressure of the flushing medium (p_FLOW) is increased by increasing the control value of a pressure control valve (15) included in the flushing system. 6. The method according to any one of the preceding claims, characterized in that, comparing the flow rate of the flushing medium (FLOW) with a second limit value (FLOW _LIMIT2 ) set for the flow rate of the flushing medium, and When the flow rate (FLOW) of the flushing medium drops below said second limit value (FLOW _LIMIT2 ), the feeding function of the rock drilling rig (1) is stopped. 7. The method according to any one of the preceding claims, characterized in that, comparing the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium with a corresponding second limit value (dFLOW _LIMIT2 ), and When the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium exceeds said second limit value ( _dFLOWLIMIT2 ), the feeding function of the rock drilling rig (1) is stopped. 8. Method according to claim 6 or 7, characterized by further pulling the drilling arrangement of the rock drilling rig (1 ) back inside the borehole (8). 9. Method according to any one of the preceding claims, characterized in that the flow rate (FLOW) of the flushing medium is compared with a setpoint (FLOW SET ) set therefor and that at the flow rate (FLOW _SET ) of the flushing medium ( FLOW) has been returned to the corresponding set value (FLOW _SET ), the pressure of the flushing medium (p_FLOW) is returned to the set value (p_FLOW _SET ) of the pressure of the flushing medium acting during normal drilling conditions. 10. Method according to any one of the preceding claims, characterized in that the flushing medium is compressed air, pressurized fluid or a mixture thereof. 11. A rock drilling rig (1) comprising means (7) for feeding a flushing medium into a borehole (8) to remove cuttings produced during drilling out of the borehole (8) , 9), a measuring device (12) for determining the flow rate (FLOW) of the flushing medium to be sent into the borehole (8), and at least one for The flow rate (FLOW) of the flushing medium controls the control unit (13) of the work of the rock drilling equipment (1), characterized in that, The measuring device (12) is configured to measure the flow rate (FLOW) of the flushing medium flowing in the flushing channel system of the rock drilling rig (1), The control unit (13) comprises means for comparing the flow rate (FLOW) of the flushing medium with a limit value (FLOW _LIMIT1 ) set for the flow rate (FLOW) of the flushing medium, and When the flow rate (FLOW) of the flushing medium falls below the limit value (FLOW _LIMIT1 ), the control unit (13) is designed to increase the pressure of the flushing medium (p_FLOW). 12. Rock drilling rig according to claim 11, characterized in that it comprises means (7, 15) for influencing the pressure (p_FLOW) of the flushing medium controlled by the control unit (13) . 13. Rock drilling rig according to claim 11 or 12, characterized in that the control unit (13) comprises: means for determining the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium, means for comparing the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium with a first limit value (dFLOW _LIMIT1 ) set for the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium, and When the rate of change (dFLOW) of the flow rate (FLOW) of the wash medium exceeds said first limit value (dFLOW _LIMIT1 ), the control unit (13) is configured to increase the pressure of the flush medium (p_FLOW). 14. Rock drilling rig according to any one of claims 11 to 13, characterized in that the control unit (13) is configured to increase the pressure (p_FLOW) of the flushing medium such that the flow rate of the flushing medium is increased to correspond to the flushing The value of the set value (FLOW _SET ) of the flow rate (FLOW) of the medium. 15. Rock drilling rig according to any one of claims 11 to 14, characterized in that the control unit (13) is configured to increase the pressure of the flushing medium (p_FLOW) to a maximum allowable value set therefor ( _{p_FLOWMAX} ). 16. Rock drilling rig according to any one of claims 12 to 15, characterized in that the pressure of the flushing medium (p_FLOW) is configured to be controlled by increasing the pressure control valve (15) included in the flushing system value increases. 17. Rock drilling rig as claimed in any one of claims 11 to 16, characterized in that The control unit (13) comprises means for comparing the flow rate (FLOW) of the flushing medium with a corresponding second limit value ( _FLOWLIMIT2 ), and The control unit (13) is configured to stop the feeding function of the rock drilling rig (1) when the flow rate (FLOW) of the flushing medium falls below said second limit value (FLOW _LIMIT2 ). 18. Rock drilling rig as claimed in any one of claims 11 to 17, characterized in that the control unit (13) comprises means for comparing the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium with a corresponding second limit value ( _dFLOWLIMIT2 ), and The control unit (13) is configured to stop the feeding function of the rock drilling rig (1) when the rate of change (dFLOW) of the flow rate (FLOW) of the flushing medium exceeds said second limit value (dFLOW _LIMIT2 ). 19. The rock drilling rig according to claim 17 or 18, characterized in that the control unit (13) is configured to control the movement of the rock drilling rig (1) to be pulled back in the borehole (8). Drilling device. 20. Rock drilling equipment according to any one of claims 11 to 19, characterized in that the control unit (13) comprises a function for comparing the flow rate (FLOW) of the flushing medium with the set value (FLOW _SET ) for comparison, and after the flow rate (FLOW) of the flushing medium has returned to the corresponding set value (FLOW _SET ), the control unit (13) is configured to return the pressure of the flushing medium (p_FLOW) to the normal chisel Setpoint for the flushing medium pressure to be applied during the drilling state (p_FLOW _SET ). 21. Rock drilling rig according to any one of claims 11 to 20, characterized in that the flushing medium is compressed air, pressurized fluid or a mixture thereof.

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